1. Field of the Invention:
The present invention relates to an air-conditioning system for vehicles having a seat heating and cooling device.
2. Description of the Related Art
Various air-conditioning units for vehicles are known as shown, for example, in Japanese Patent Laid-open Publication No. HEI 6-293209. Additional to the air-conditioner unit, a seat heater or a seat heating and cooling device may be used as an auxiliary air-conditioner.
One example of the known seat heater is disclosed in Japanese Patent Laid-open Publication No. SHO 58-116216. The disclosed seat heater is a flexible mat having a heating element embedded therein. In use, the seat heater is placed over a seat of the vehicle and powered by a battery of the vehicle. To secure quick heat-up of the seat heater in a low-temperature environment, a first thermostat set to turn on at 10.degree. C. and turn off at a relatively high temperature such as 40.degree. C. is provided between the battery and the heating element. A second thermostat set to turn on and off within an on-off differential temperature of the first thermostat is connected in parallel to the first thermostat to control a power feed to the heating element so as to keep a steady-state heated condition of the heating element after the first thermostat is turned off.
A typical example of the seat heating and cooling device is disclosed in Japanese Patent Laid-open Publication No. HEI 5-277020. The disclosed heating and cooling device is a built-in unit assembled integrally with a seat of the vehicle and generally comprises a number of air nozzles formed in the seat, a space defined below the seat and held in fluid communication with the air nozzles, a Peltier element (heating element) disposed within the space, and an electric fan disposed within the space for forcing air downstream toward the air nozzle across the Peltier element.
The seat heater or the seat heating and cooling device is used in combination with the air-conditioner, and the battery is used as a common power supply. However, they are driven separately in accordance with different items of information. In other words, the seat heater or the seat heating and cooling device operates independently from operating conditions of the air-conditioner unit, and vice versa. Accordingly, in order to keep the vehicle passenger compartment in a desired condition, the driver or a passenger of the vehicle is required to set operating conditions of the air-conditioner unit and operating conditions of the seat heater or seat heating and cooling device, separately. Such setting operation is tedious and time-consuming. Furthermore, while the air-conditioner unit and the seat heater or the seat heating and cooling device are in operation, the compartment temperature and the seat temperature vary separately, requiring e-setting of the operating conditions of the respective units which is tedious and time-consuming.